Preparation of ethanolamine



Patented Dec. 20, 1949 UNI-*2r s'lffrAf'rEs PATENT" oFF?! NoIDr'miringxz Application ctober, 1945,f-wy Seriall No. 620,195

This inventipn i relates f 05 the ,preparation @of new fcompositions; ofmatter. fro'ri tertiary olnes l andiormaldehyde cyanhydri fand.tolprocess'es fortheir preparatiorxL.

Ihe layer-ali process of inyention includes fourA steps Whiohmy'jbeillstratd. by" way of example referenceto-{isbhtylrie and formal- `vdehyde cyarhydrirfsthefsourbe'material. LThe by the reactio'nofispbutylhe witHfo'rmamehydef tained; (s)arraiteate'arocesstbthat'empioyed for the formation. ofdi-t-butoxyethylamineis provided whr'eb'y the't-butoxyethylalmine' of4the An object of the inyentionisto"proiidenew f alkoxysubstitutedntrile's "andiamnes: i Another butjoxyethylarnine"`"Still'anotherfobject is toipro vdefor thepreparatinbf ltherabovefproductsra action of a tertiary oleflnev with formaldehyde-vdrogenatio'rfi of thathternediatelproductfor the prparatidr'l of analkoxyethylarhine; 4 `Yet 1an: other object is to provide a processofipreia'rng`4` amine;` other objects and advantages of they in.1veiition will hereinaftj'fappar.

1n the firsts'tepfof'the processgatertiaryole# fine such forexampleasiscibiitylene "is l1'*`ea`.cted f effected byvpressuring'ra@sea yesserftontainmg" fofmameiryde:eyarmydfin f with' isnbutylee-fnrmixing Vliquidi'sobutylene Withfforialdehyde cyl anhydrin in` asuitablefreaction"yessel'fand Cong-jfl with one `part otforin'aldehyde"cyanhydrin `The tweefo" .findLz'olry C.,M,pre'ferab1 y are .temperaTture vbetween around; 60"t`c "100C. under a pres sure rangingbetween"`10 'andf100 atmospheres?" although higher. pressuresn'iay'be'employed if desii-d.' As ycatalyst"foi'v'thveg reaction, "anysuitable' inorganic acid maybe"employedsueh forex'am--" ple',` assulfuricacid, hydrchloric "acid, boron fluoride (or itsadditiofprod'ucts); paratolu'ene"V sulfonc acid or any suchaoid oracidsaltyvhich` will give a lpHin waterb'les'stha' 6. The' catalyst maybesediin'rounts ranging from 1/3 to 5 molar percent.

This sten f"th-^'1e;tin,may be illustrated as proceeding in accord withthe equation:

which formulatesfthe'-:interaction-of isobuty-leney withformaldehydefcyanhydrin to :produce t-butoxyacetorlitriler'` Themore-detai1edpractice-of; this Lstepof the l inventionis illustratedbyptheefollowngexam-v plesyin e which` partssareby `Weight unless.other- Wisejstated. l f

Example `1.--Al mixture' of 13.7 parts of formaldehyde cyanhydrn,( ).4part of ,concentrated sulfuric acid,zand 160 parts of isobutyle'ne'wasprocessed in a silver-lined pressure resistingv shaker tube atf90".for-1.75 hours, and a pressure" of 255 p. s. i. Distillatin ofthereactonproduct yielded- :23 ,parts of t-butoxyacetonitrile, which boilsat 449/55 mmorzsb/rmm. Its refractive i index, 111,25, isllAOi. InDnerLm.underthese conditions 85% of the formaldehyde cyanhydrin" charged waseonierted'to t-butoiiya'cetonitrile.

ExampleA 2.-The processfof Example 41 was repeated .usi-ng `21.0 parts,of `fforrnaldehyde cyan" hydrin, 1` partfsulfu'i'oacidiandA 1601narts'of isobutylene, the miiitui'fbeing'fprocessed for' 2 hours at-80C. and abote. i. An excellent l yildfof 'tebutoiiyaetonitril A'yi/as'obtained. y'

The reactionL asfldescribd in the above exarnples inay be duplicatdbytheuse f'hther .ter-

tiary. olenes such, forexaniple, as 2methy1bu tene-1, .z-thy'i battue-1,fz-.methyl pentenefi, 2

vde 4Vcorresponding tertiary` 'a'lkoxyacetontrilesl '.[nfaccordwith'thfe Second Stpll'of the process,

tri1e,"is ,converted'to acorrjes'pondin'g amine by! lfiydrog'eratiorhzThis maybe effected' and is pref" erably4 effected inth'e liquid-phaseemploying as catalysts vforthe:reabtio'nia; suitable' activehydrogenatio'n' foatalystfsubhl? for" example, 'f as those made/troninickecobalt, fused"*cono'e'rcobalt,V

copper chromite, or mixtures thereof or similar catalysts, preferredcatalyst for hydrogenation to t-butoxyethylamine being an alkali-freeprecipitated cobalt oxide catalyst.

The hydrogenation can be conducted in the liquid or vapor phase attemperatures ranging between 25 and 200 C. and at pressures between 1and 1000 atmospheres although it is preferred to conduct thehydrogenation of the nitrile at temperatures between 75 and 150 C. andunder :u

pressures between 20 and 1000 atmospheres.

It has been found that by-produ-ct formation is inhibited duringhydrogenation, yields are increased, and the reaction made to proceedmore smoothly with the production favoring the primary amine as productif there be present during the reaction from 1 to 20 moles of ammoniaper mole of the nitrile. 1f desired, the nitrile to be hydrogenated maybe dissolved in aqueous ammonia or the nitrile may be dissolved insuitable solvent such as methanol, di(isobuty1) ether, dioxane,cyclohexane, or 1,3-dioxolane, or other suitable solvent which is notdecomposed or hydrogenated during the reaction or decomposed by theammonia added to the solution.

This, the second vstep of the process, may be illustrated by theequations:

Equation 2 illustrates the hydrogenation of the nitrile tot-butoxyethylamine while Equation 2a, in which is a positive integer andy is less than illustrates the conversion of the nitrile tod-t-butoxyethylamine although as shown some mono t-butoxyethylamine mayalso be present.

Generally normal hydrogenation, either in the presence or the absence ofa solvent described aforesaid, will produce both the primary and thesecondary amine. It may be desirable to conduct the reaction in order tofavor the formation ol the primary amine or the formation of thesecondary amine. If it is desired to favor the formation of the primaryamine, this can be accomplished by conducting the hydrogenation in thepresence of in the order of preferably to molar proportions of ammoniawith hydrogen pressures around 700 atmospheres and temperatures in theneighborhood of 120 C. for discontinuous operation while for continuousoperation a lower proportion of ammonia is suggested in the order of 5molar proportions with a somewhat lower pressure in the order of 300atmospheres. Moreover, as has been indicated, cobalt catalysts favor theformation of primary amines while nickel catalysts tend to givemixtures.

The second step of the process for the formation of the monoamine may beconducted in accord with this example.

Example 3.-A charge of 64.8 parts of t-butoxyacetonitrile, 130 parts ofanhydrous ammonia, and 40 parts of cobalt catalyst was divided andprocessed in two silver-lined shaker tubes at 1Z0-138 for 1 hour underhydrogen pressure of 600-800 atmospheres. Distillation of the reactionproduct yielded 63.2 parts (94% conversion) of t-butoxyethylamine,neutral equivalent 118.1, 118.4 vs. 117 theoretical. This product has aboiliii) alkali,

4 ing point of 64/64mm., and its refractive index, H1325, is 1.4128.

To favor the formation of the di-t-alkoxye ethylamine it is preferableto carry out the hy drcgenation in the presence of a suitable solvent.The solvents :may be used to the extent of at least 20% by weight andthe hydrogenation is preferably conducted at somewhat lower pressuresranging between 20 and 100 atmospheres, the hydrogenation proceeding forabout 10-200 minutes in batchwise operation. Longer periods ofhydrogenation will tend to favor the formation oi' the diamine.

These examples illustrate the hydrogenation of 1 the nitrile by aprocess which favors the formation of the di-t-butoxyethylamine.

Example 4.-A mixture of 33.0 parts of t-butoxyacetonitrile, 33.7 partsof cyclohexane, and 5 parts of Raney nickel catalyst was processed under150 p. s. i. hydrogen pressure in a silverlined shaker tube at -125 fortwo hours. Distil'lation gave the following fractions: (1) a 5.6 partsforeshot shown by titration to contain 4.2 parts of t-butoxyethylamine,(2) 15.1 parts of t-butoxyethylamine, neutral equivalent 116.9, 118.2,(3) a 3.6 parts intermediate fraction, neutrai equivalent 135.5, 137.7,containing 2.9 parts t-butcxyethylamine and 0.7 part di-(t-butoxyethyl)amine, and (4) 5.3 parts of di-(t-butoxyethyl) amine, neutral equivalent225.7, 225.7 vs. 217 theoretical. The boiling range of fraction 4 was79P1/3 mm. Thus t-butoxyethylamine was obtained in 65% conversion whiledi-(tbutoxyethyl) amine was obtained 1n 19% conversion.

vlitzwmzple 5.-When a mixture of 23.8 Darts of t-butoxyacetonitrile,75.9 parts of cyclohexane, and 10 parts of Raneynickel catalyst wasprocessed under 450 p. s. i. hydrogen pressure at 92- 108 for 15minutes, the conversion tot-butoxyethylamine was 69% and the conversionto di- (t-butoxyethyl) amine was 10.5%.

Similarly the tertiary alkoxyethylamines prepared from tertiary olefinesother than is-obutylene can be hydrogenated by either of theabovedescribed processes for obtaining on the one hand a mixture of theprimary and secondary amines and on the other an excess of the primaryamine.

An alternate method for the preparation of the di-t-butoxyethylamine,referred to herein as the third step, is provided by a process whereinthe primary amine of the second step is converted to the secondaryamine, preferably in the presence of hydrogen. It has been found thatthe second step of the process, while it gives under the indicatedconditions both the primary and secondary amines, the former can beconverted to the latter in excellent yields if it be separated from thesecondary amine which can be readily done by distillation and processedin the presence of hydrogen and a suitable hydrogenation catalyst. Whilethe catalyst described for use in the second step may be'employed forthis purpose, and will convert appreciable quantities of the primarytothe secondary amine, it is pre.- ferred to use a supported nickelcatalyst such as nickel on kieselguhr. Cobalt and nickel hydrogenationcatalysts which contain incorporated in the catalyst during preparationor during activation, such as the Raney type catalysts, may also .beused. The process of this step is preferably conducted at a somewhathigher temperature, say

between and 300 with preferred tempera-V memes:

(3) 2 (CH3 eCOCI-IZCHQNHZ* toxyacetonitrile was converted to thesecondary amine.

Example 7.-A mixture of 136.8 parts of t-butoxyethylamine and parts ofnickel-on-kieselguhr catalyst was processed in a silver-lined shakertube under 150-'7'70 p. s. i. hydrogen pressure at 198-228" for 75minutes. Distillation of the reaction product gave di-(t-butoxyethy1)amine, B. P. 94/1 mm., neutral equivalent 217, 219 vs. 217 theoretical,in 65% conversion (based on the t-butoxyethylamine charged) and 79%yield (based on the tnbutoxyethylamine not recovered).

Similarly, the higher molecular Weight mono t-alkoxyethylamines preparedby the hydrogenation of the t-alkoxyacetonitrile prepared from e:

isooleiines higher than isobutylene can be treated in accord withexamples 6 and 7 to convert the monoamine to the diamine.

rihe mono and di-t-alkoxyethylamines of the above or other processes arehydrolyzed by the fourth step to a mono or diethanolamine. Thehydrolysis step is illustrated by Equations 4 and 5.

Equation 4 formulates the hydrolysis of monomeric tbutoxyethylamine toethanolamine and Equation 5 the hydrolysis of di-t-butoxyethylamine todiethanolamine.

The hydrolysis step is conducetd by cooling an aqueous solution of themono or diamine, slowly adding a hydrolysis catalyst such as sulfuricacid, and refluxing under normal pressure while taking oi the volatilehydrolysis products leaving in the reaction Vessel the mono ordiethanolamine. Any suitable hydrolysis catalyst may be Lil) employedsuch, for example, as sulfuric acid, v

phosphoric acid, paratoluenesulfonic acid and the like or mixturesthereof and these catalysts should be employed in sufficient amounts andconcentrations to effect the hydrolysis at reflux temperatures within atleast 6 or 8 hours. If desired, the hydrolysis may be eiected underpressure and the corresponding temperatures above the normal boilingpoint of the aqueous mixture or, contrary/wise, under reduced pressureswith temperatures below the boiling point of the mixture. In the lattercase, a longer perod of? timergenerally is. required-f to. effect thehydrolysis.

The'- Examples 81 and.'` 9. illustrate. the fourth.: step of` the*4process'. whereinthe parts. are by; .l weight unlessotherwiselindicated. l

Erum-plellf-A `reaction vesselltted with :a recondenser was charged.withA 25.6Y parts of mono t'butoxyethylamine.and 59.4.parts of Water:The rf-zsulting`` mixture wascooledi to` about 5" C.`

'- and 21`.8=partsl ofi` 100% sulfuric acid. graduallyu added' withstirring, the temperature.. not being.

permitted to rise appreciably above30. C. during the addition. Thetemperature4 of the mixture Wasthenraisedftoits boiling point, whichranged fromY` '1'8"to 98? C: and. refluxed in this range.y until no moravolatile products distilled over;` The products was cooled, 17.5 partsof caustic soda added to neutrailze the acid and the water then removedat approximately 40 mm. pressure and thereafter the ethanolaminedistilled from the dehydrated mixture at a pressure of approximately 1mm. An 89.3% conversion of the isobutoxyethylarnine to ethanolamine wasobtained.

Eample 9.-A reaction vessel similar to that described in Example 8 wascharged with 16.3 parts oi di-t-butoxyethylamine and 18.2 parts ofwater. The amine-water mixture was cooled and to the cooled solution'7.7 parts of 100% sulfuric was gradually added at such a rate that thetemperature of the solution was maintained below approximately 30 C. Themixture was heated to reflux temperature and refluxed for about 6 hoursto drive oi the isobutylene and other products formed during thehydrolysis which were volatile at refluxing temperature. The reactionmixture was then treated in accord with the process described in Example'i' and approximately a 77% conversion of the di-t-butoxyethylamine todiethanolamine was obtained.

The products of the reaction have many uses. All are valuableintermediates for making many organic compounds. The mono anddi-t-butoxyethylarnines may be used directly as thickeners, non-polardetergents, softeners and plasticizers for regenerated cellulose,cellulose ethers, esters, and the like while the ethanolamines have manywell known uses in the arts.

I claim:

1. A process for the preparation of an ethanolamine of the groupconsisting of mono and diethanolamines simultaneously with an olenewhich comprises splitting, an aqueous solution of, atertiary-alkoxyethanolamine to an ethanolamine and an olene by graduallyadding with cooling to a temperature below 30 C. a hydrolysis catalystto the aqueous solution, the catalyst being of the group consisting ofsulfuric acid, phosphoric acid, and paratoluene sulfuric acid, andthereafter heating under reiiux temperatures the resulting solution, rstseparating the olene and finally recovering the ethanolamine from thereaction mixture.

2. A process for the preparation of ethanolamine simultaneously withisobutylene which comprises splitting, an aqueous solution of,tertiary-butoxyethanolamine to ethanolamine and isobutylene by graduallyadding thereto with cooling to a temperature below 30 C. a hydrolysiscatalvst, heating under reflux temperature the resulting solution. thecatalyst being of the group consisting of sulfuric acid, phosphoricacid, and paratoluene sulionic acid, and thereafter recoveringisobutylene and ethanolamine from the reaction mixture.

awww.

3. A process for the preparation of diethanolamine simultaneously withisobutylene which comprises splitting, an aqueous solution of,ditertiary-isobutoxyethylamine to diethanolamine and isobutylene byadding with cooling to a temperature below 30 C. a hydrolysis catalystto with cooling to a temperature below 30 C., to an aqueous solution ofa tertiary-alkoxyethanolamine, thereafter heating the resulting solutionunder reux at a temperature below 98 C. and finally recovering anethanolamine and an olefine from the reaction mixture.

W'ILLIAM F. GRESHAM.

REFERENCES CITED The following references are of record in the le ofthis patent:

Richter Organic Chemistry, translated by Spielmann (2nd Ed.) vol. I,page 127, published by P. Blakistons Sons 8; Co., Philadelphia, Pa.

l Certicate of Correction l Patent N o. 2,491,659 December 20, 1949WILLIAM F.v GRESHAM It is hereby certified that errors appear in theprinted specification of the above numbered patent requiring correctionas follows:

Column 5, line 52, before +2(CH3)2 insert NH; line 57, for conducetdread conducted; column 6, line 17, for products read product; line 18,for neutrailze read neutralize; line 30, after the syllable furie insertacid; line 59, for "sulfuric read salfom'c; lines 60 and 61, fortemperatures read temperature;

and that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Oiice.

Signed and sealed this 25th day of April, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommsioner of Patente. t ,A m

